It is known to use daughter electronics cards that are connected at one of their ends to one or more motherboards and/or to isolated connectors that are connected to cabling.
The backplane connections of a rack may for example be made up of one or more connectors, and the positioning and locking of the connection between daughter cards and rack backplane connectors may be performed in various ways.
The rack backplane connector(s) may be fastened rigidly to the rack or may be floatingly mounted transversely and/or axially in order to accommodate positioning defects.
In another known variant, the connectors are mounted floatingly in the axial direction by a resilient element that compensates for differences in depth between rack backplane connectors.
In another known variant, transverse guidance is provided by the connector itself, in the form of grooves and projections that slide in one another.
Transverse guidance may also be provided independently of the connectors, with the help of metal centering fingers.
Cards may also be locked to the rack via the rack backplane connector, by means of clips, resilient pins, screws, or levers.
In a variant, card locking may be offset from the electronics card and the structure of the rack, e.g. with locking levers that are installed directly on the printed circuit of the electronics card or locking screws that, in a variant, are incorporated in the chassis that supports said printed circuit.
Known solutions for floatingly mounted rack backplane connectors generally present the defect of the connector not touching the rack back plates, thereby giving rise to gaps that encourage leakage of electromagnetic interference.
Furthermore, a locking system for locking the daughter electronics card to the rack that is incorporated in a rack backplane connector may present the drawbacks of being difficult to access for disconnection, of not providing clear visibility of a good connection, of not coping with problems of coupling depth when a plurality of connectors are mounted on the same electronics card, or indeed of not enabling the electronics card as a whole to be stiffened, which can give rise to problems with respect to the vibration performance of the electronics card in severe-environment applications, and of not enabling the rack backplane connectors and the electronics card to be mounted in any order.
Furthermore, it is known to use so-called “external” techniques for locking the electronics card to the rack, which techniques consist in combining longitudinal locking by screw fastening and transverse locking by means of a prismatic slideway, e.g. of the Calmark® type.
Locking merely by screw fastening does not make it possible to take up longitudinal clearances directly in the event of the rack having multiple connectors, and it does not make it simple to control the coupling force applied to the connectors. These two drawbacks then need to be mitigated by the connectors at the rack backplane. Furthermore, prismatic slideway systems do not make it possible to overcome continuous coupling forces.
To remedy those drawbacks, proposals have been made firstly to provide a connection that is floating along the connection axis over a plurality of connectors situated at the rack backplane, with this floating connection being provided by a resilient element such as a spring washer or a helical spring.
Nevertheless, such a floating connection system can require resilient elements that are very stiff, with having movement strokes of the order of several millimeters. Springs that satisfy such conditions are relatively bulky compared with the dimensions of connectors.
Furthermore, incorporating resilient elements in rack backplane connectors can make them more complex, giving rise to an increase in the sizes of the plates of connectors in order to house the resilient elements and the spring-retaining system.
Finally, a floating mount for connectors in a rack can lead to the connectors not pressing against the metal plate at the back of the rack, thereby leaving openings that lead to leakage of electromagnetic interference (EMI).
Furthermore, proposals have also been made to lock an electronics card to a rack by using systems of levers positioned on the electronics card, enabling the electronics card to be inserted in the rack.
Nevertheless, such locking systems do not provide permanent compensation for forces tending towards disconnection, which forces are generated by sealing systems, and those locking systems are unsuitable for compensating longitudinal clearances that are too great.
There exists a need to satisfy to the above-mentioned drawbacks in full or in part.